ML083180852

Waterford Steam Electric Station, Unit 3 - Acceptance Review Email

ML083180852
Person / Time
Site:	Waterford
Issue date:	11/05/2008
From:	Nakanishi T T NRC/NRR/DSS
To:	Kalyanam N K Plant Licensing Branch IV
Kalyanam N, NRR/DLPM, 415-1480
Shared Package
ML083180654	List: ML083180752 ML083180852
References
Download: ML083180852 (2)

Text

Entergy Nuclear (licensee) submitted a license application to revise the Waterford Steam Electric Station Unit 3 (Waterford) licensing basis to reflect the new spent fuel pool (SFP) criticality analysis. The licensee performed the new analysis to credit soluble boron in the fuel storage racks for both Standard and Next Generation Fuel (NGF).

Currently, there is not a generically approved methodology for performing SFP criticality analysis. Therefore, each plant-specific submittal must provide reasonable assurance that the applied methodology provides conservative results. The staff completed the acceptance review of the application and finds that the information delineated below is necessary for the staff to conduct the detailed technical review.

1) Burnup profile:

The licensee states that, "Calculations are conservatively performed with the axial burnup distribution shown in Table 5.3 (see Section 5.3) and with an axially constant burnup, and the higher reactivity is used in the analyses." However, the application lacks information demonstrating that these distributed and axially constant profiles are bounding for the fuel assemblies at Waterford. Please describe the methodology used for the profile selection.

How were the effects of using blanketed fuel and/or operating with control rods/axial power shaping rods considered?

The application identifies two distributed profiles for two burnup intervals: one for 25 GWD/T and another for 25 GWD/T. How was the transition point determined?

2) Burnup uncertainty:

The licensee states that burnup uncertainty was applied in accordance with the staff guidance Reference 1). However, the application does not show how the reactivity decrement was calculated. Provide the enrichment and burnup combinations used to determine the decrement.

3) Depletion parameters:

NUREG/CR-6665, "Review and Prioritization of Technical Issues Related to Burnup Credit for LWR Fuel" (Reference 2), recommends using the maximum fuel and core outlet temperature. Table 5.2 of HI-2084014 identifies the average temperatures for the fuel and moderator. State that assumed temperatures for the fuel and moderator bound all projected operating conditions at Waterford if that is the case. If not, provide justification for using less than the maximum temperature.

The application identifies 1000 ppm as the bounding soluble boron concentration. Provide the cycle-average soluble boron concentration at Waterford.

In addition to moderator/fuel temperature and soluble boron concentration the licensee is also requested to address the other core depletion parameters indicated in NUREG/CR-6665 as well. 4) Fuel rod and assembly parameters:

The application states that, "Tolerance calculations were performed for pure water only since the presence of soluble boron in the pool lowers reactivity and reactivity effects of tolerances, and therefore the pure water case bounds the soluble boron case." Please quantitatively support this assertion.

5) CASMO-4 In support of the amendment request, CASMO-4 is used to determine the reactivity effects due to rack tolerances, assembly design, and pool temperature. The application does not provide any validation of the code for these uses. Please justify CASMO-4 for these purposes.

6) Soluble Boron Requirements:

The application provides no discussion on the soluble boron methodology. Please explain how the soluble boron requirements are determined.

References:

1. NRC Memorandum from L. Kopp to T. Collins, Guidance on the Regulatory Requirements for Criticality Analysis of Fuel Storage at Light-Water Reactor Power Plants," August 19, 1998 (ADAMS ML003728001). 2. NUREG/CR-6665, "Review and Prioritization of Technical Issues Related to Burnup Credit for LWR Fuel"